Optional Type-B Interface; Video Interface - Epson ActionLaser 1600 Service Manual

Principles of Operation

Optional Type-B Interface

This printer supports an EPSON Type-B optional interface, which is controlled by
the INH and BIF signals from the E05A93 (IC24).

Video Interface

ASIC E05A92 maps the SRAM into a memory space different from the system
memory. The CPU transmits data from the V-RAM (in the system RAM) to the
SRAM using ASIC E05A92. The ASIC cell converts the image data in the SRAM
from parallel to serial, synchronizes it, and then transmits it to the engine
controller board. In other words, the SRAM is a temporary buffer used to
transmit the image data to the engine controller board. This serial image data is
the VIDEO signal of video interface.
The signal lines of the internal video interface circuit (the C125 MAIN board and
engine controller board) can be broadly divided into four groups. The first group
(PRINT, CPRDY, EPRDY, and PRDY) gives the status of either the video
controller or engine controller and indicates whether they are ready to
communicate with each other or ready to start the printing operation. The second
group (VSYNC, HSYNC) is the synchronizing signal for the printing operation.
The third group (VIDEO) is the serial video data signal. The fourth group (CMD,
SRCLK, CTBSY, and ETBSY) is used to transfer the commands (from the video
controller) or the status (from the engine controller) for printer mechanism
control. Except VIDEO, PRINT, VSINC, and HSYNC signals are controlled by
ASIC E05A93.
This printer has BiRITech and EMGTech functions standard. These functions
modify the VIDEO signal using ASIC E05A92.
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